Best Video cam currently available?
Any better than a C100 and EF-lens for anything $5K and under...?
No, not if you get the c100 II with a pdaf sensor for autofocus.
The only other low cost option is a 70d or a 7d2. Both have excellent (like amazing excellent autofocus) the 70d has touch screen with the ability to move the focusing spot when shooting or quickly before you start rolling, where the 7d2 doesn't have an articulating or a touch screen.
The only difference between the two is the 70d does not have a headphone jack (which can be added with a sound recorder and a small cage. You can trick out a 70d for about $2500 which is a bargain if you have ef mount glass.
The only issue with a 70d, 7d2 vs a c100 is obviously sound connectors and the fact the sensors are set up for line skipping to get to 1920 across. That means you have to be aware of alaising and moire in some situations (though any camera under 2.5 k across can have these issues).
It's funny, we'll shoot the 70d next to our RED ONEs and Scarlet MX, and 75% of the footage used always comes from the 70d and not because it's technically as good (it's not close) but because it's more fluid, real and loose.
It all depends on what you shoot, but if you go the c100 look at the II rather than the original because if it autofocuses close to the 70d you'll use it all the time.
IMO
BC